cxx11 1.1 port group / -stdlib=macports-libstc++ may not be setting up paths correctly for i386 builds

[Kenneth F. Cunningham]

Yeah, well this one may well be NTBF, but I thought I would mention it.

During a recent buildbot build of Pingus using the cxx11 1.1 PortGroup on i386, the build fails with an error suggesting that when building with clang-4.0 against libstdc++ from libgcc6, in i386 mode, the proper flavour headers aren't found. 

I would suspect if we dug into the path settings in Marcus' macports-libstdc++ modifications, we might find that this situation isn't covered. (I had to do some finagling with the paths to make this issue work out on clang-3.8 PPC as well.) I'm not sure how much interest there might be in covering off this corner case. -- Ken

[  2%] Building CXX object CMakeFiles/tinygettext.dir/external/tinygettext/src/dictionary.cpp.o
/opt/local/bin/clang++-mp-4.0   -I/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_games_pingus/pingus/work/pingus-06afdabb6b27c1314bb1d90a05d467697b72be58/src -I/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_games_pingus/pingus/work/pingus-06afdabb6b27c1314bb1d90a05d467697b72be58/external/tinygettext/include -I/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_games_pingus/pingus/work/pingus-06afdabb6b27c1314bb1d90a05d467697b72be58/external/sexp-cpp/include -I/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_games_pingus/pingus/work/pingus-06afdabb6b27c1314bb1d90a05d467697b72be58/external/logmich/include  -pipe -Os -D_GLIBCXX_USE_CXX11_ABI=0 -stdlib=macports-libstdc++ -std=c++1y -arch i386 -mmacosx-version-min=10.6   -o CMakeFiles/tinygettext.dir/external/tinygettext/src/dictionary.cpp.o -c /opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_games_pingus/pingus/work/pingus-06afdabb6b27c1314bb1d90a05d467697b72be58/external/tinygettext/src/dictionary.cpp
In file included from /opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_games_pingus/pingus/work/pingus-06afdabb6b27c1314bb1d90a05d467697b72be58/external/logmich/src/log.cpp:20:
In file included from /opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_games_pingus/pingus/work/pingus-06afdabb6b27c1314bb1d90a05d467697b72be58/external/logmich/include/logmich/log.hpp:23:
/opt/local/include/gcc6/c++/string:38:10: fatal error: 'bits/c++config.h' file not found
In file included from /opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_games_pingus/pingus/work/pingus-06afdabb6b27c1314bb1d90a05d467697b72be58/external/logmich/src/logger.cpp:20#include <bits/c++config.h>
:
In file included from /opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_games_pingus/pingus/work/pingus-06afdabb6b27c1314bb1d90a05d467697b72be58/external/logmich/include/logmich/log.hpp:23:
/opt/local/include/gcc6/c++/string:38:10: fatal error: 'bits/c++config.h' file not found
#include <bits/c++config.h>
         ^~~~~~~~~~~~~~~~~~


full log
<https://build.macports.org/builders/ports-10.6_i386_legacy-builder/builds/25036/steps/install-port/logs/stdio>